This invention relates to a self-actuating blow forward firearm, and more particularly to a self-actuating blow forward firearm designed for use as an automatic or semi-automatic weapon and having a fixed breech block and a moving barrel.
In a self-actuating firearm, the combustion or explosion of the propellant from a round of ammunition is used to perform one or more of the functions of the operating cycle of the firearm. Typically, the gas from the combustion or explosion is used to propel the bullet down the barrel of the firearm and is also used to activate the firing cycle for the next round of ammunition. A more complete explanation of self-actuating firearms is contained in U.S. Pat. No. 2,865,256 (Marsh), which is incorporated herein by this reference.
Previously in self-loading automatic or semi-automatic firearms, it has been necessary to use a mechanically locked breech system to prevent the breech block from moving backward upon firing of the firearm. Any backward movement of the breech block will inhibit the forward movement of the bullet out of the barrel of the firearm. These mechanically locked breech block designs suffer from the drawback of high manufacturing costs and the necessity for periodic replacement of mechanical parts during periods of extended use.
Instead of mechanically locking the breech block, it has been previously proposed to use what is known as a "blowback" type design which generally utilizes a very heavy breech block to allow sufficient delay in the rearward movement of the breech block to prevent the premature opening of the rear portion of the firing chamber during the high pressure portion of the firing cycle. Such a design is likewise used to encourage the forward movement of the bullet down the barrel of the firearm due to the effect of the natural expansion of the exploding gases caused by the firing of the firearm. Typical of such a heavy unlocked breech block design is the Thompson submachine gun or the Israeli Uzi submachine gun.
These designs using a heavy breech block suffer from the drawback of excessive weight which limits their effectiveness for military applications as well as the drawback that the heavy breech block moving inside the weapon receiver limits the ability of the firearm to be used as a high speed automatic weapon due to the excessive vibration.
It is an object of the present invention to provide a self-actuating blow forward firearm which has the ability to be used as a high speed automatic weapon and also is relatively lightweight in design and inexpensive to manufacture.
It is a feature of the present invention to provide a self-actuating blow forward firearm with a fixed breech block coupled with a moving barrel, the movement of the barrel resulting from the drag of the bullet along the interior of the barrel toward the muzzle of the firearm and from the use of a gas piston attached to the barrel, and is further enhanced by the addition of a muzzle brake.
It is an advantage of the present invention that an automatic or semi-automatic self-actuating blow forward firearm is provided which is both lightweight and inexpensive to manufacture, which eliminates the need for a mechanically locked breech block or a heavy unlocked breech block and which is extremely compact because the receiver length necessary for the movement of the breech block is eliminated.